Dendritic and Hyperbranched Polymers. James E. Hanson. Department of Chemistry and Biochemistry. Seton Hall University. South Orange, New Jersey ...
Dendritic and Hyperbranched Polymers James E. Hanson Department of Chemistry and Biochemistry Seton Hall University South Orange, New Jersey
Polymer Architectures ...
...
linear
OH
CO2H
O
O
HO
O
O
O
O
OH
HO
O
HO O
O
O
OH
hyperbranched
HO
O
O
O
O
O
OH
dendritic
O
Degree of Branching D +T D+T+L
%DB =
X 100% OH
CO2H
O
O
O
O
D O
L
O
HO
O
OH
T
O
HO
HO O
T hyperbranched DB = 80%
D
D
O
OH
O
O
HO
O
O
O
O
OH
T
T
T T dendritic DB = 100%
T
Dendrimer Synthesis Divergent NH3
NH
H2N
1. methyl acrylate (3 equivalents)
O
NH N
2. ethylene diamine (excess)
1. methyl acrylate (excess) 2. ethylene diamine (excess)
NH
H 2N
core
O
NH2
O generation 1
H2N NH
NH
O NH
N
O H 2N
O
NH N
HN N H2N
NH2
O
HN
N
1. methyl acrylate (excess)
O
NH
2. ethylene diamine (excess) HN
O
O
O O
NH2
NH NH2 generation 2
generation 3, etc.
Dendrimer Synthesis Convergent CO2CH3
HO
CO2CH3
CH2OH
benzyl bromide K2CO3 THF 18-crown-6
OH
KBH4 LiCl
O
THF
O
O
O
1 2 G1CO2CH3
3 G1OH
CH2Br CBr4 P(C6H5)3 THF
1 K2CO3
O
O
THF 18-crown-6
5 G2CO2CH3
KBH4 LiCl THF
6 G2OH
4 G1Br CBr4 P(C6H5)3 THF
10 G3Br
7 G2Br 1 K2CO3 THF 18-crown-6
1 K2CO3 THF 18-crown-6
11 G4CO2CH3
8 G3CO2CH3 KBH4 LiCl THF
KBH4 LiCl THF
12 G4OH
9 G3OH MsCl (CH3CH2)3N THF
CBr4 P(C6H5)3 THF
13 G4OMs
Hyperbranched Polymer Synthesis SH
SH
K2CO3 Cl Cl
NMP 150oC
S S
Cl S
Cl
S S
Cl
Cl
S Cl
Cl Cl
Cl
New Methods for Synthesis: Poly(arylmethyl Ether) Dendrimers
• Original Frechet synthesis based on 3,5dihydroxybenzyl alcohol • Polymers above 4th generation difficult • Activation step problematic (Ph3P, CBr4) • Electrophilic focal group (benzyl bromide)
Monomer Synthesis OH
CH3O2C
CO2CH3
C16H33SO2Cl triethylamine toluene
OSO2C16H33
CH3O2C
CO2CH3 3
2 OSO2C16H33 KBH4, LiCl
SOCl2
THF OH
OH 4
OSO2C16H33
OSO2C16H33 NaBr, CH2Br2 DMF (2X)
Cl
Cl 5
Br
Br 1
Monodendron Synthesis OH
OSO2C16H33
OH
OSO2C16H33 NaOH Br
Br
K2CO3 acetone
1 monomer 10 G3-hds
NaOH ethanol
O
ethanol
O
O
6 G1-hds 11 G3-OH
O
1 K2CO3 acetone
8 G2-hds
1
14 G5-hds
NaOH ethanol
9 G2-OH
1 K2CO3 acetone
15 G5-OH
1 K2CO3 acetone
7 G1-OH
1
NaOH
12 G4-hds
K2CO3 acetone
O
13 G4-OH
ethanol O
O
O
O
O
O
O
O
O
O
O
O
O O
O
O
O
O
O
O
O
O
O O
O
O
O
O
O
O
O O
K2CO3 acetone
O
O
O
O
O
O
O
O
O
O
O
O
O O
O
O
O
O
O
O
O
O
O
O
O O
O
OSO2C16H33
O
O O
O O
O O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O O
O
O
O
O
O
16 G6-hds
O
O O
O
O
O
O
O
NaOH ethanol
NMR
G3-hds
Tridendron Synthesis O(CH2)8Br
OH
K2CO3 18-crown-6
+ O
O
Br(CH2)8O
acetone
O(CH2)8Br
C8
O
O
G1OH O
O
O
O
O
O
O
O
O
O
G1C8
Size Exclusion Chromatography
SEC of G1OH – G5OH
SEC Data - Monodendrons Compound
Nominal MW
LS Mw
Polydispersity
G1-hds
595
601
1.02
G2-hds
1019
1015
1.01
G3-hds
1868
1819
1.01
G4-hds
3566
3546
1.01
G5-hds
6963
6512
1.01
G6-hds
13754
13529
1.01
G1-OH
306
397
1.01
G2-OH
731
713
1.01
G3-OH
1580
1494
1.01
G4-OH
3278
3303
1.01
G5-OH
6674
6581
1.02
SEC Data - Tridendrons
Compound
Nominal MW
LS Mw
Polydispersity
C8G0
783
825
1.00
C8G1
1374
1387
1.00
C8G2
2636
2412
1.01
C8G3
5190
5183
1.00
C8G4
10278
10369
1.00
Summary: Poly(arylmethyl Ether) Dendrimer Synthesis • Robust synthetic method, simple coupling and deprotection chemistry • Monodendrons up to sixth generation prepared • Nucleophilic focal group • Apparently indistinguishable from isomeric Frechet poly(arylmethyl ether) dendrimers
Photophysics of Pyrene Labeled Poly(arylmethyl Ether) Monodendrons • Little known about size and dynamics of dendritic polymer • Pyrene as a photophysical reporter well established in polymer science • Ham effect, O2 quenching, excimer formation, rotational depolarization
Monodendron Synthesis CO2CH3
HO
CO2CH3
CH2OH
benzyl bromide K2CO3 THF 18-crown-6
OH
KBH4 LiCl
O
THF
O
O
O
1 2 G1CO2CH3
3 G1OH
CH2Br CBr4 P(C6H5)3
1 K2CO3
THF
THF 18-crown-6
O
O
5 G2CO2CH3
KBH4 LiCl THF
6 G2OH
4 G1Br CBr4 P(C6H5)3 THF
10 G3Br
7 G2Br 1 K2CO3 THF 18-crown-6
1 K2CO3 THF 18-crown-6
11 G4CO2CH3
8 G3CO2CH3 KBH4 LiCl THF
KBH4 LiCl THF
12 G4OH
9 G3OH MsCl (CH3CH2)3N THF
CBr4 P(C6H5)3 THF
13 G4OMs
Pyrene Labeling
OH
OR RX K2CO3 THF 18-crown-6
O
O O
O
O
O
15 MeOPy, R = CH3 , X = I 16 G0OPy, R = C6H5CH2 , X = Br 17 G1OPy, R = G1 , X = Br 18 G2OPy, R = G2 , X = Br 19 G3OPy, R = G3 , X = Br 20 G4OPy, R = G4 , X = OMs
O
O
O
O
O
O O
O
O
O
O O
O
O
O
O
O
O
O O
O O
O O
G4Py 20
O
SEC – Pyrene Labeled Monodendrons
Compound
Nominal MW
LS Mw
Polydispersity
G1Pyrene
521
543
1.02
G2Pyrene
945
932
1.02
G3Pyrene
1795
1822
1.01
G4Pyrene
3492
3495
1.01
Absorbance and Emission Spectra
Absorbance spectrum: 1-methoxypyrene
Fluorescence spectrum: 1-methoxypyrene
Frequency Domain Fluorometry
Fluorescence Modulation Data 1-G4OP (20) in THF Degassed
1-G4OP (20) in THF Oxygen Saturated
90
1.0
90
80
80
50 40 0.4 30 20
0.2
10
60
Phase
0.6
Modulation
60
0.8
70
0.6
50 40
0.4
30 20
0.2
10
0
0.0 2
2
3
4
5
6
7
9
Frequency Phase exp. Phase calc. Modulation exp. Modulation calc.
11
14 17
(MHz)
21
26
32
40
0
0.0 15 18
22
26
31
38
46
55
Frequency Phase exp. Phase calc. Modulation exp. Modulation calc.
66 79
(MHz)
95 115 138 166 200
Modulation
0.8
70
Phase
1.0
Fluorescence Lifetimes Compound
τo nsec
τ, air nsec
τ, O2 nsec
kq (x 1010)
Pyrene
346
16.8
3.8
3.7
MeOPy
20.1
10.2
3.4
3.4
G0Py
20.9
10.2
3.3
3.4
G1Py
20.5
10.8
3.8
3.0
G2Py
20.8
11.2
3.9
2.8
G3Py
20.7
11.3
4.1
2.7
G4Py
20.7
11.4
4.5
2.3
Fluorescence Quenching • Quenching data obtained in 3 solvents: acetonitrile, THF, cyclohexane • Two oxygen concentrations: air saturated and O2 saturated • Quenching rates by Stern-Volmer analysis: τo/τ = 1 + kqτo[O2]
Smoluchowski Analysis • The Smoluchowski equation is used to describe quenching: kq = α4π(Dox + Dpy)RoN • Quenching data does not provide an internally consistent data set: Dox from MeOPy won’t work with G4Py
Diffusion Coefficients by PFG-NMR • NMR with a z-gradient allows measurement of diffusion coefficients ln (I) = D ( 2)
ln (I)
10
9
0 .0
0 .1
0 .2
0 .3 2 2 (T /m )
0 .4
0 .5
Diffusion Data (THF) Compoun d
Dpy (cm2sec-1)a
RStokes (Å)b
VStokes (Å3)c
ρStokes (D/Å3)d
Vfree (Å3)e
Pyrene
1.7 x 10-5 f
2.8
92
2.19
-
MeOPy 15
1.7 x 10-5
2.8
92
2.52
-
G0Py 16
1.3 x 10-5
3.7
210
1.47
-
G1Py 17
0.97 x 10-5
4.9
490
1.06
25
G2Py 18
0.78 x 10-5
6.1
950
0.99
106
G3Py 19
0.48 x 10-5
10
4200
0.43
2600
G4Py 20
0.34 x 10-5
14
11500
0.30
8400
Radii vs. MW 15
THF
a
R (A)
10
5
solid line: log
0 0
1000
2000
3000
4000
M W (D )
dashed line: power
6
acetonitrile
b
R (A)
5
4
3
2 0
1000
2000
M W (D )
3000
4000
Density vs MW 3
ρ (D/A3)
2
1
0 0
1000
2000 MW (D)
3000
4000
o acetonitrile i THF
Shielding Model R' φ R
pyrene
α calc
R'
monodendron
R' 2 R sin −1 R + R' = 1− 2πR
Analysis of Quenching and Diffusion Data (THF) Compound
αexp
αcalc
Prel
DO2 + Dpy (cm2sec1)
DO2 (cm2sec1)
ηeff
Pyrene
-
1.00
-
8.82 x 10-5
7.12 x 10-5
-
MeOPy 15
-
1.00
-
8.05 x 10-5
6.35 x 10-5
1.00
G0Py 16
-
0.92
-
8.17 x 10-5
6.87 x 10-5
0.92
G1Py 17
0.97
0.86
0.8
7.09 x 10-5
6.12 x 10-5
1.04
G2Py 18
0.94
0.82
0.7
6.71 x 10-5
5.93 x 10-5
1.07
G3Py 19
0.94
0.75
0.7
6.44 x 10-5
5.96 x 10-5
1.07
G4Py 20
0.82
0.70
0.4
5.46 x 10-5
5.12 x 10-5
1.24
Iodine Quenching
Iodine Quenching: Static Quenching
Summary: Quenching and Diffusion • Combination of quenching data and diffusion coefficients gives insight into dendrimer shape, size, and dynamics • Smaller monodendrons are less of a barrier than larger monodendrons, with more open structures • Solvent is important: structures are more extended in THF than acetonitrile • Static quenching with iodine
Excimer Formation • Pyrene forms excimers in solution: excited state dimers • Excimer kinetics first worked out by Birks in the 1940s; more recent models are also known • Pyrene excimer formation has been widely used to study the dynamics of polymers in solution
Excimer Kinetics hν M
k1 M* + M
kD D*
k-1
kM +
+
Q
Q
kQM M + Q
kQD 2M + Q
M + M
Monomer and Excimer Fluorescence
Methoxypyrene in THF
a 5 x 10-2 b 1 x 10-2 c 1 x 10-3
Monomer Lifetime Data
Excimer Lifetime Data
Excimer Kinetic Analysis
Methoxypyrene in THF: a = λ1; b = λ2
Excimer Kinetics in THF Compound
k1 M-1s-1
k-1 s-1
K M-1
-∆ ∆G kcal/mol
Pyrene
5.56 x 109
2.53 x106
2.20 x103
4.56
MeOPy
2.12 x 109
5.88 x106
3.60 x102
3.48
G0Py
2.10 x 109
6.24 x106
3.36 x102
3.44
(MeO)2G0Py
1.95 x 109
5.84 x106
3.33 x102
3.44
G1Py
1.99 x 109
5.59 x106
3.34 x102
3.44
G2Py
1.85 x 109
5.57 x106
3.32 x102
3.41
Oxygen Quenching Compound
kQD, acetonitrile
kQD, THF
Pyrene 1
3.40x1010
2.86 x1010
MeOPy 2
3.33 x1010
2.84 x1010
G0Py 3
3.28 x1010
2.81 x1010
G0’Py 4
3.23 x1010
2.78 x1010
G1Py 5
3.19 x1010
2.33 x1010
G2Py 6
---b
2.27 x1010
Iodine Quenching
Iodine Quenching
Pyrene 1
ACN kQD (M-1 s-1) 2.16x1010
THF kQD (M-1 s-1) 1.26x1010
CH kQD (M-1 s-1) 1.22x1010
MeOPy 2
1.95x1010
1.23x1010
1.21x1010
G0Py 3
1.74x1010
1.06x1010
1.08x1010
G0’Py 4
1.66x1010
9.96x109
1.08x1010
G1Py 5
1.38x1010
9.89 x109
--- b
G2Py 6
--- b
9.87x109
--- b
Compound
Excimer Studies: Summary • Alkoxypyrenes form excimers, but these excimers are less stable than pyrene excimers • Smaller pyrene labeled monodendrons form excimers; diffusion coefficients do not fully explain excimer formation rates • Excimer fluorescence is quenched by oxygen and iodine
Dendritic Coatings for Capillary Electrochromatography • Capillary electrophoresis is a powerful separation method • Coating of capillary walls can add chromatographic effect • Separation of neutrals and cations is then possible
Capillary Electrophoresis / Electrochromatography
Coating Methodology CH2OH (C2H5O)3Si O
NCO
O
Toluene (2) O (C2H5O)3Si
N H
O
O
(9) G1 carbamate
O
EOF
Separation - Neutrals
Separation - Proteins
Separation – Pyrrolopyridine Isomers
Summary – Capillary Electrochromatography • Dendritic coatings are useful in capillary electrochromatography • Dendritic coatings reduce and stabilize EOF • Dendritic coatings allow separation of neutrals and basic compounds, including proteins • Dendritic coatings appear to be superior to linear coatings (i.e. C18)
Hyperbranched Poly(phenylene Sulfide) and Poly(phenylene Sulfone)
• Poly(phenylene sulfide) and poly(phenylene sulfone) are important engineering polymers • Hyperbranched versions have potential for rheology modification
Synthesis Linear Poly(phenylene sulfide) Na2S Cl
S
Cl
n
Hyperbranched Poly(phenylene sulfide) SH
SH
K2CO3 Cl Cl
NMP 150oC
S S
Cl S
Cl
S S
Cl
Cl
S Cl
Cl Cl
Cl
Molecular Model G3 Sulfide
SEC
DSC
TGA
MALDI
Hyperbranched Poly(phenylene Sulfone) SH
SO3H
H2O2 S
SO2
S
Cl S
Cl
S S
SO2
Cl
Cl
Cl
Cl
Cl
SO2
Cl
Cl
Cl Cl
SO2 SO2
S Cl
SO2
Cl
Cl Cl
Cl
IR
DSC
TGA
Summary: Hyperbranched PPS and PPSO2 • Hyperbranched poly(phenylene sulfide) readily prepared from dichlorothiophenol. • Hyperbranched poly(phenylene sulfone) from oxidation of HPPS • HPPS has higher Tg (~120 oC), apparently noncrystalline • HPPSO2 has high Tg > 200 oC, insoluble
Acknowledgements Arylmethyl Sulfones Neil Gargiulo Angela Harris Yazmin Hernandez Don Motta Denise Pingor
Photobase Generators Kathryn Jensen Toni Watt
Dendritic and Hyperbranched Polymers Shana Kelley Jeanne Riley Berk Wajiha Khan Tammy Tyler Shannon Alfredo Mellace Hye Jung Han Qiuxia Lucy Zhao Helen Chao Sibel Alkan Jim Wilckens Elizabeth Miklius Dr. W.R.Murphy & Group
Molecular Imprinting & Nanoparticles Wajiha Khan Sueyuan Li Jim Wilckens Katie Poremba Guida Reis
Polymer Photophysics Sean Healy Jeanne Riley Berk
Lucent Technologies Bell Laboratories Petroleum Research Fund Research Corporation National Science Foundation ACS Project SEED Seton Hall University Research Council
